Method of distilling petroleum



E. F. BURCH.

METHOD OF DISTILLING PETROLEUM.

APPLICATION FILED APR. 23, 1917.

1,396,249. Patented Nov. 8, 1921.

SHEETS-SHEET I.

E. F. BURCH.

METHOD OF DISTILLING PETROLEUM.

APPLICATION FILED APR.23, 1917.

1,396,249. Patented Nov. 8, 1921.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFlCE.

"ELI r. nuncn, or LAUREL srnmes, NEW JERSEY.

METHOD OF DIS'IILLING PETROLEUM.

Specification of Letters Patent. Patented NOV. 8, 1921.

Application i'iled April 23, 1917. Serial No. 163,826.

ing is a specification.

The principal object of my invention is to provide a new and improved method for distilling certain kinds of petroleum. An-

other object of my invention is to provide such a method that shall secure the lubricating oil content of the petroleum with as little diminution as possible due to converfslon thereof into other components. another object of my invention is to provide Still an improvement in the art of distilling pc- I troleum by which the proportion of lubricating oil obtained therefrom shall be maintained as high as practicable; All these objects andothers will be better understood in connection. with consideration of specific examples of my method. Accordingly, I

now proceed in some detail to describe a specific embodiment of my invention, but it will be understood that this is only by way of ekample and that the scope OfthG-lllVGl'l-i tion is defined in the appended claims.

Referring to the drawings, Figure 1 is a side elevation of apparatus that maybe used in practising my improved method;

Fig. 2 is atop plan view of the same, and Fig. '3 is a diagrammatic representation of apparatus that may beused in connection with this method.

I Referring more particularly to Fig. 3, I fill the retort or still A about half full of Mexican petroleum, introducing it through the opening normally closed by the plug 21. A fire is made under theretort A and a gentle heatapplied to drive all the lighter gases-and vapors through the pipe 1 and through the condenser B. The vapors condense and run down through the look-box 22 into the tank C where they collect, but the more permanent gases are drawn from the box 22 through the suction pipe 4 to the pump D and discharged thence through the pipe 13 into the gas tank E. In the look-box 22 there is a window 23 through which the condensate from the condenser B can be observed. The gas in the tank E is subject to a pressure which may be regulated by the weights 24; and a part of this gas is discharged through the pipe 14: and valve 30 to the perforated pipe 16 under the petroare provided at 24 and 25, so that the temperature of the liquid within the still A can be observed and also the temperature of the vapor as it leaves the still. After a sufficient uantity of gas has accumulated in the tank part of it can be taken to the burner 26 and used for heating the still. If more gas accumulates in the tank E, than can be used in this way it canbe diverted as desired through the branch pipe 27 Pressure gages are provided at 28 and 29. The gage 28 shows the pressure substantially on the suction side of the pump D and the gage 29 shows the pressure of the gas as it is delivered to the perforated pipe 1%. In practice, I have found that it works well to have the pressure at the gage 28 about one pound below atmospheric pressure and the ressure at the gage 29 about four pounds a ove atmospheric pressure.

When the distilling process is commenced, of course thelighter oils or naphthas come off first for a given moderate temperature maintained in the still A. It is convenient afterthese have been practically all driven over to the tank C to make a cut and empty the contents of tank C and operate the still for a second stage at a higher temperature, driving oil the intermediate fuel oils and collecting them in the tank C. After these have been practically all ob tained it .is convenient to make another cut, and empty the tank C of its contents and operate at a still higher temperature to get the lubricating oils from the petroleum now remaining in the still The number of cuts to be made in this way during the distillation of a single batch of the petroleum is more or less an arbitrary matter and is simply for convenience in effecting the ultimate desired separation of the various oils in the petroleum. The important feature of my process is that by continuously pumping the gases back into the still through the perforated pipe 16, I can carry the process to a point where only coke will be left in the still A, and yet I can obtain the maximum proportion of lubricating oils from the petroleum.

Whether or not the cuts are made to separate the lubricating oils in stages from the lighter oils, it is a comparatively easy mat- -ter according to well known methods to complete the refining of the lubricating oils after they have been collected by condensation in the tank C.

If it were attempted to distil the Mexican petroleum merely by'the application of heat and without the introduction of the gases through the perforated pipe 16, as by completely closing the valve 30, the result would be that at the higher temperatures necessary for driving off the heavier lubricating oils, these oils would not be obtained in anywhere near the same degree of purity as when the gas in introduced in accordance with the normal procedure of my method. In the absence of the gas introduced through the pipe 16, the application of heat to the still at this later stage would apparently decompose the lubricating oils, breaking up their molecules, and giving a large proportion of fuel oil only a little heavier than kerosene and of much less value than the lubricating oil. This is easily demonstrated experimentally, for when lubricating oils are beinggiven off with say a temperature at the thermometer 24C of about 400 F. and with the gas flowing normally through the pipe 16, if the gas flow is interrupted by closing down the valve 30, the supply of oil entering the tank C as viewed through the window 23 will stop, and no condensate will go over until the temperaturehas been raised considerably, say to 500 F. Then, however, the condensate will be of entirely different character, not the comparatively heavy lubricating oil that was obtained before the valve 30 was closed, but lighter oil, only slightly heavier than kerosene, the

socalled fuel oil.

The Mexican oil with which I have found my improved method to be especially advantageous is a double base oil, that is it has both paraffin and asphalt as its basic constituents. Tn attempting to distil it merely by the application of heat, the lightest in-. gredients are obtained without difiiculty but as soon as the process progresses to the point of raising the temperature to drive off the lubricating oils, they appear to be broken down and decomposed into lower members of the series, and these apparent decomposition products are principally fuel oils of the least value of the various petroleum derivatives. Attempting to distil this Mexican oil by the mere application of heat actually gives lighter oils at thehigher temperatures than were obtained by the moderate temperatures preceding, apparently for the reason that at the higher temperatures fit of my invention.

I find that in every stage of my process there is enough permanent gas given off to maintain a sufiicient supply through the pipe 16. Of course, this gas circulates around and around through the system and its quantity is increased by evolution from the petroleum in the still A so that it accumulates in the tank E and the excess can be used to maintain the fire under the still and for other purposes. I 7

It is not indispensable to a realization of the advantages of my method that the condensate should be removed from the tank C in cuts. It may be collected there altogether until the residue in the still A is mere coke, but this will be with the assurance that the mixture in the tank C has an undiminished proportion of the higher members of the series, namely, the valuable and desirable lubricating oils. Inasmuch as it would be necessary, however, to redistil the contents of the tank C to separate the lighter oils from the lubricating oils, it is a matter or convenience to make this separation at the first, by cuts as described. The coke that forms in the still A as a result of my process is very porous and easily broken up and removed. This is one of the advantages of my process, for without the introduction of the gas as described, the coke might be dense, hard and diiiicult to remove.

T have described my improved method as a matter of practice rather than oi theory. Actually it obtains from the petroleum a large proportion of. the higher lubricating ingredients, a much larger proportion than I have been able to obtain in any other way. Just why this is, I do not consider to be vital to practicing my invention. It is possible that the blowing in of the gas through the perforated pipe 16 may produce some hydrogenation of the oils remaining in the petroleum, but the determination of such points of theory of operation is not necessary to a practical realization of the bene- Referring to Figs. -1 and 2 of the drawings, l have'provided two condensers B and B and it will be seen that the pipes and. valves are so connected that I can either take the distilled gases and vapors through one condenser E on the way to the tank U and the pump 1), or I can take these gases and vapors through the two condensers B and B in succession, collectin the condensates in the respective tanks 6 and C.

As to certain of its subject matter, this aplication is continuation of application erial No. 103,930, filed June 6, 1916.

'Havin thus described my invention, I declare t at what I claim as new and desire to secure by Letters Patent, is p The process of distilling petroleum oil of heating a charge of the petroleum in a still to vaporize only the lightest constituents,

. condensing the light oils out of the evolved gases at a temperature not sufliciently low to condense all of the evolved ases, collecting the gases that are not con ensed at the temperature of condensation, increasing the heating of the still and passing these noncondensed gases back through the heated petroleum, and condensing the vapors evolved and collecting the non-condensed gases and repassing these inon-condensed gases through the petroleum in the still, and continuing the heating of the still with a rise in temperature at each step and the passing of the gases through it and the condensation of the distillates and the collection of the non-condensed gases until the'desired distillates have been separated from the charge, so as to avoid cracking of the constituents of the petroleum and to obtain a greater yield of the more valuable products such as lubricating oils from a given quantity of petroleum base of high asphaltic content.

ELI BURCH. 

